In Czochralski silicon crystal pullers, the silicon monoxide (SiO) generation from the reaction between molten silicon (Si) and the quartz crucible (SiO2) starts at about 1150.degree. C. At this temperature SiO constitutes the major volatile component, besides inert gas.
The vapor pressure of SiO at 1150.degree. C. is 0.05 millimeters of mercury. The SiO vapors condense on the cooler parts of the crystal puller and they also react with hot graphite (the heater), leading to carbon monoxide (CO) generation. Carbon monoxide is the major precursor for carbon contribution in the finished silicon crystal.
The suppression of SiO generation is important for reduction of both oxygen and carbon in silicon crystals.
Conventional Czochralski crystal furnaces have been equipped with an external magnetic field. This magnetic field imparts unique properties to semiconductor materials, one of which is to reduce the oxygen content of the crystal.
Conventional magnetic Czochralski crystal furnaces require an expensive external power supply and magnet to provide the magnetic field. Operation and maintenance of this equipment is expensive and cost prohibitive for most applications.